The present invention relates to a gas/liquid separator and more particularly to a gas/liquid separator in which during operation, a rotary motion is imparted to a stream of liquid-bearing gas inside a separation chamber, whereby liquid particles are thrust outwardly by virtue of their weight and impinge on the inner surface of the wall of the separation chamber where they coalesce into a liquid film which can be separately discharged from the separation chamber via, for example, openings in the wall thereof. Gases leave the separation chamber via a gas outlet, which is substantially concentrical with the longitudinal axis of the separation chamber.
Gas/liquid separators of the above type are widely used in the chemical and the gas treating industries. It should be noted that the term gas is taken throughout this specification and the claims also to invariably include vapor.
Examples of gas/liquid separators in which liquid is separated from a stream of gas by imparting a swirl motion to the gas are, among others, described in British patent specification 1,123,546 and more recently in European patent application 82201420. Both publications describe gas/liquid separators having a plurality of parallel, vertically extending cylindrical walls laterally enclosing separation spaces and mounted in or over openings of a tray, wherein the gas inlets and gas outlets are positioned at opposite sides of the tray. The spaces enclosed by the cylindrical walls are provided with swirl imparting means formed by inclined, preferably fixed, vanes for imparting a rotary motion to a gas/liquid mixture introduced into the tubular elements via their open lower ends. The separated liquid may be discharged from the separation spaces partly through liquid discharge openings provided in the cylindrical walls and partly over the upper ends of said walls. European patent application 82201420 relates to an improved variant of the above generally known type of equipment. This improved separator is in particular intended for an efficient separation of gas/ liquid mixtures at high gas velocities and/or high liquid loadings. The improvement according to the latter patent consists, among others, in the application of primary gas outlet tubes for discharging gas directly from the separation spaces in combination with secondary gas outlet tubes for discharging gas entrained by separated liquid from enclosed liquid collecting spaces surrounding the cylindrical walls defining the separation spaces. The combination of cylindrical wall with liquid discharge openings and rotation imparting means will be hereinafter indicated with the expression swirl tube.
Depending on the dimensions of the swirl tubes, and of the primary and secondary gas outlets, the latter patent separator may be operated at very high gas throughputs per swirl tube without substantial impairment of the separation efficiency. At a given configuration and given dimensions of the swirl tubes, and of the primary and the secondary gas outlet tubes, the required throughput in a gas/liquid separator provided with swirl tubes, determines the number of swirl tubes which should be applied. The number of swirl tubes in its turn determines the cross sectional area of the separator vessel, which normally is vertically arranged for operation. Since the vessel itself forms a major contribution to the total manufacturing costs of a gas/ liquid separator it is worthwhile to design vessels having dimensions, i.e., length and diameter, as small as possible at a given required throughput of the vessel. If the required throughput necessitates the use of a large number of swirl tubes, it may be economically more attractive to install the swirl tubes on a horizontal tray in a horizontally extending cylindrical vessel, wherein the swirl tube tray divides the interior of the vessel into a gas inlet channel and a gas outlet channel. The available height may also necessitate the application of horizontal vessels instead of vertical vessels.
Although a horizontal separator with swirl tubes may be attractive from a manufacturing point of view, two main operational problems occur when such a vessel with a relatively large tray for mounting a large number of swirl tubes, is to be operated at high gas load factors. These problems are in the first place, gas maldistribution over and in the swirl tube tray resulting in a poor separation efficiency and, in the second place, problems adhered with the liquid discharge from the swirl tube tray. In the below these phenomena will be discussed in detail.